netdev - [PATCH net 09/15] i40evf: remove ndo_poll

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Date:   Fri, 21 Sep 2018 15:27:46 -0700
From:   Eric Dumazet <edumazet@...gle.com>
To:     "David S . Miller" <davem@...emloft.net>
Cc:     netdev <netdev@...r.kernel.org>,
        Eric Dumazet <edumazet@...gle.com>,
        Michael Chan <michael.chan@...adcom.com>,
        Ariel Elior <ariel.elior@...ium.com>,
        Eric Dumazet <eric.dumazet@...il.com>,
        Tariq Toukan <tariqt@...lanox.com>,
        Saeed Mahameed <saeedm@...lanox.com>,
        Jeff Kirsher <jeffrey.t.kirsher@...el.com>,
        Jakub Kicinski <jakub.kicinski@...ronome.com>,
        Song Liu <songliubraving@...com>,
        Jay Vosburgh <j.vosburgh@...il.com>,
        Veaceslav Falico <vfalico@...il.com>,
        Andy Gospodarek <andy@...yhouse.net>
Subject: [PATCH net 09/15] i40evf: remove ndo_poll_controller

As diagnosed by Song Liu, ndo_poll_controller() can
be very dangerous on loaded hosts, since the cpu
calling ndo_poll_controller() might steal all NAPI
contexts (for all RX/TX queues of the NIC). This capture
can last for unlimited amount of time, since one
cpu is generally not able to drain all the queues under load.

i40evf uses NAPI for TX completions, so we better let core
networking stack call the napi->poll() to avoid the capture.

Signed-off-by: Eric Dumazet <edumazet@...gle.com>
Cc: Jeff Kirsher <jeffrey.t.kirsher@...el.com>
---
 .../net/ethernet/intel/i40evf/i40evf_main.c   | 26 -------------------
 1 file changed, 26 deletions(-)

diff --git a/drivers/net/ethernet/intel/i40evf/i40evf_main.c b/drivers/net/ethernet/intel/i40evf/i40evf_main.c
index 5906c1c1d19d82d7e37b0a891e457fea792b4153..fef6d892ed4cfe5ae293aa2fe01ef38a257c47bf 100644
--- a/drivers/net/ethernet/intel/i40evf/i40evf_main.c
+++ b/drivers/net/ethernet/intel/i40evf/i40evf_main.c
@@ -396,29 +396,6 @@ static void i40evf_map_rings_to_vectors(struct i40evf_adapter *adapter)
 	adapter->aq_required |= I40EVF_FLAG_AQ_MAP_VECTORS;
 }
 
-#ifdef CONFIG_NET_POLL_CONTROLLER
-/**
- * i40evf_netpoll - A Polling 'interrupt' handler
- * @netdev: network interface device structure
- *
- * This is used by netconsole to send skbs without having to re-enable
- * interrupts.  It's not called while the normal interrupt routine is executing.
- **/
-static void i40evf_netpoll(struct net_device *netdev)
-{
-	struct i40evf_adapter *adapter = netdev_priv(netdev);
-	int q_vectors = adapter->num_msix_vectors - NONQ_VECS;
-	int i;
-
-	/* if interface is down do nothing */
-	if (test_bit(__I40E_VSI_DOWN, adapter->vsi.state))
-		return;
-
-	for (i = 0; i < q_vectors; i++)
-		i40evf_msix_clean_rings(0, &adapter->q_vectors[i]);
-}
-
-#endif
 /**
  * i40evf_irq_affinity_notify - Callback for affinity changes
  * @notify: context as to what irq was changed
@@ -3229,9 +3206,6 @@ static const struct net_device_ops i40evf_netdev_ops = {
 	.ndo_features_check	= i40evf_features_check,
 	.ndo_fix_features	= i40evf_fix_features,
 	.ndo_set_features	= i40evf_set_features,
-#ifdef CONFIG_NET_POLL_CONTROLLER
-	.ndo_poll_controller	= i40evf_netpoll,
-#endif
 	.ndo_setup_tc		= i40evf_setup_tc,
 };
 
-- 
2.19.0.444.g18242da7ef-goog